The present invention relates to method of forming superconduting oxide ceramic materials having high critical densities of superconduting current.
Superconducting oxide ceramics comprising rare metals, alkalline earth metals and copper have been known as superconduting materials having relatively high critical temperature. Such an oxide superconducting ceramic of this type, however, could not pass a superconducting current therethrough at a sufficient current density, when fabricated in wire form. This is considered because the effective cross sectional area thereof may be small as compared with the theoretical area due to its porous structure.
Recently, a relatively high current density has been obtained by melting the superconducting oxide material and recrystallizing the same, which procedure is called the melting method. The superconducting current density has been as high as 10000 A/cm.sup.2 by this procedure. The melting method, however, has to be done in a crucible which has been particularly prepared in order to endure temperatures higher than 1300.degree. C. For this reason, it has been required to decrease the melting point of the ceramics. The introduction of excessive copper oxide decreases the melting point. However, this procedure inevitably influences the superconductivity of the ceramic.